# Human Capital Quality Channel

## E1: Z → human_capital
- Dependent variable: `human_capital`
- N = 3910, Countries = 137, R² = 0.6922, ρ = 0.990

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| Z_1 | 1.1457 | 0.1364 | *** |
| Z_2 | -0.0828 | 0.0207 | *** |
| Z_3 | 0.0015 | 0.0009 | * |
| rgdp_growth | -0.0009 | 0.0001 | *** |
| kaopen | 0.0040 | 0.0012 | *** |
| log_gdp_pc | 0.2268 | 0.0088 | *** |

## E2: human_capital → rd_efficiency
- Dependent variable: `rd_efficiency`
- N = 619, Countries = 40, R² = 0.1237, ρ = 0.979

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| human_capital | 0.1683 | 0.2845 |  |
| rgdp_growth | 0.0016 | 0.0030 |  |
| kaopen | -0.0019 | 0.0337 |  |
| log_gdp_pc | 0.3384 | 0.1606 | ** |

## E3: Z → patents_pm (no HC)
- Dependent variable: `patents_per_million`
- N = 1163, Countries = 57, R² = 0.1740, ρ = 0.990

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| Z_1 | -2239.3903 | 1196.9653 | * |
| Z_2 | 348.8532 | 178.7117 | * |
| Z_3 | -13.6325 | 7.2973 | * |
| rgdp_growth | -0.7391 | 0.8426 |  |
| kaopen | 5.7565 | 10.8785 |  |
| log_gdp_pc | 43.1974 | 81.0168 |  |

## E4: Z → patents_pm (with HC)
- Dependent variable: `patents_per_million`
- N = 1021, Countries = 46, R² = 0.1847, ρ = 0.990

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| Z_1 | -2619.0924 | 1360.2095 | * |
| Z_2 | 413.6048 | 205.9819 | ** |
| Z_3 | -16.5350 | 8.4795 | * |
| human_capital | 7.8210 | 160.6882 |  |
| rgdp_growth | -1.6157 | 1.1788 |  |
| kaopen | 6.6751 | 12.0630 |  |
| log_gdp_pc | 65.6940 | 101.8327 |  |

## E5: Z + Z1×HC → patents_pm
- Dependent variable: `patents_per_million`
- N = 1021, Countries = 46, R² = 0.2343, ρ = 0.990

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| Z_1 | -2800.5708 | 1360.8667 | ** |
| Z_2 | 416.4906 | 205.6558 | ** |
| Z_3 | -18.3297 | 8.5104 | ** |
| human_capital | 252.2262 | 199.3812 |  |
| Z1_x_hc | 210.4051 | 101.9163 | ** |
| rgdp_growth | -1.5042 | 1.1781 |  |
| kaopen | 5.7042 | 12.0528 |  |
| log_gdp_pc | 48.8804 | 101.9948 |  |

## E6: Z → rd_efficiency (with HC)
- Dependent variable: `rd_efficiency`
- N = 619, Countries = 40, R² = 0.1589, ρ = 0.980

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| Z_1 | -2.2140 | 3.9026 |  |
| Z_2 | 0.5253 | 0.5567 |  |
| Z_3 | -0.0260 | 0.0220 |  |
| human_capital | 0.1775 | 0.3229 |  |
| rgdp_growth | 0.0025 | 0.0031 |  |
| kaopen | 0.0024 | 0.0337 |  |
| log_gdp_pc | 0.1482 | 0.2101 |  |

## E7: Z + Z1×HC → rd_efficiency
- Dependent variable: `rd_efficiency`
- N = 619, Countries = 40, R² = 0.0746, ρ = 0.990

| Variable | Coefficient | Std Error | Sig |
|:---------|:------------|:----------|:----|
| Z_1 | -0.8293 | 4.1505 |  |
| Z_2 | 0.4962 | 0.5875 |  |
| Z_3 | -0.0188 | 0.0235 |  |
| human_capital | -1.0371 | 0.4617 | ** |
| Z1_x_hc | -0.9217 | 0.2481 | *** |
| rgdp_growth | 0.0021 | 0.0030 |  |
| kaopen | 0.0117 | 0.0332 |  |
| log_gdp_pc | 0.2208 | 0.2463 |  |
